【作者】 林良彪；

【导师】 陈洪德； 侯明才；

【作者基本信息】 成都理工大学 ， 古生物学与地层学， 2005， 硕士

【摘要】 前人对川西前陆盆地和龙门山冲断带的研究历史悠久,并取得了一系列的研究成果,但也存在许多研究的薄弱环节,这主要体现在:①上三叠统须家河组地层的划分和对比问题;②对川西前陆盆地须家河组物源未作系统的研究;③晚三叠世须家河期海陆过渡关系不明确。这些问题的解决,对研究区油气勘探及预测有利油气勘探目标区具有重大的现实意义。 在前人研究的基础之上,本文以沉积学、构造地质学、盆地分析理论等为指导,通过对川西前陆盆地上三叠统须家河组的地层对比、物源分析、沉积相类型及其相带展布特征、前陆盆地的构造演化特征、以及古地理的演化等方面的研究,对上述问题进行探讨、分析,并重点对研究区上三叠统须家河组沉积相、岩相古地理演化进行研究。通过研究表明: 1、对研究区晚三叠世的地层进行归并、划分,并统一命名为须家河组,且划分为五段。 2、研究区物源主要来自西边:须一、须二期,物源主要来自于松潘—甘孜褶皱带及西边已隆升的岛屿;须三～须五期,物源主要来自于龙门山逆冲推覆体。且须三～须五期,因受龙门山逆冲推覆体强烈运动的影响,使得古生代—早中三叠世碳酸盐岩地层遭受剥蚀,在龙门山北段出现了大量的碳酸盐岩岩屑;而在龙门山南段,由于龙门山逆冲推覆体运动不强烈,只将晚三叠世早期(T₃x^1～2)沉积的地层剥蚀,因而出现了大量的粉砂岩、泥页岩岩屑;龙门山中段作为北段与南段的过渡带,其沉积特征也明显的表现出了过渡性。 3、须家河期研究区主要发育冲积扇、辫状河三角洲、湖泊、海相三角洲、滨岸、海湾和浅海七种主要的沉积相类型,并详细讨论了各个沉积相的沉积特征。 4、研究区在须家河期主要受控于龙门山逆冲推覆体的形成、发展,并经历了由被动大陆边缘阶段（T₃x¹）→前陆盆地形成阶段（T₃x²→T₃x³）→前陆盆地发展阶段（T₃x⁴→T₃x⁵）三个演化时期,古地理演化相应的经历了由海相环境→海陆过渡相环境→陆相环境的转变。 5、须四早期（T₃x⁴）,受安县运动的影响,龙门山逆冲推覆体褶皱成山,使得整个四川盆地进入了陆相沉积环境,川西前陆盆地由形成期转化为发展期。更多还原

【Abstract】 West Sichuan Foreland Basin and Longmenshan thrust belt have been studied in a long time. Many progresses have been achieved in these areas, but there are three major problems remained, which include the division and correlation of the Xujiahe Formation of upper Triassic, the deficit in systematically studying the provenance of Xujiahe Formation and the ambiguity in confirming the time when the sedimentary environment changes from marine to continental of the late Triassic in West Sichuan Foreland Basin.On the basis of the theories of sedimentology, tectonics and the principle of basin analysis. The author try to solve above problems by stratigraphy relationship of studied area, analysis of provenance, types of sedimentary facies and the spreading characteristic of facies zone, the characteristic of tectonic evolution and paleogeographic evolution in West Sichuan foreland Basin. And the author studies in detail sedimentary facies, paleogeographic characteristics and evolution of the Xujiahe Formation of upper Triassic in studied area. The thesis has gained the following achievements:1. Merging and dividing the stratigraphy of late Triassic, and name unitedly Xujiahe Formation which is divided five sections.2. The provenance areas of studying area mainly lain on the Songpan-Ganzi Fold Belt and western island which have uplifted in the first and second stages of the Xujiahe sedimentary period (T₃x¹²). Clastic material came from the Longmenshan thrust belt in the third to fifth stages of the Xujiahe sedimentary period (T₃x³⁵). At the same time, with the Longmenshan Thrust belt taking place strongly tectonic movement in the north sector of the Longmenshan, there were a large of carbonate clastic debris came from the Paleozoic-the middle Triassic carbonate strata depositing in the north sector of the Foreland Basin. On the contrary, there were a large of siltstone and mudstone or shale debris which came from T₃x¹² strata depositing in the south sector of the south sector of the Foreland Basin, because the movement of the Longmenshan Thrust belt was weaker in the south sector than in the north sector.更多还原